Article
Physics, Fluids & Plasmas
H. Q. Wang, D. M. Thomas, A. W. Leonard, X. X. Ma, H. Y. Guo, A. L. Moser, J. G. Watkins, F. Scotti, C. Lasnier, M. E. Fenstermacher, A. G. McLean, M. W. Shafer, B. Grierson, J. Ren, T. H. Osborne
Summary: Experiments in DIII-D demonstrate that higher plasma current and heating power combined with impurity seeding facilitate divertor detachment and improve plasma performance in a closed divertor compared to an open divertor.
Article
Physics, Fluids & Plasmas
T. M. Wilks, L. A. Morton, D. M. Kriete, M. Knolker, P. B. Snyder, K. Barada, C. Paz-Soldan, T. Rhodes, K. H. Burrell, X. Chen, J. W. Hughes
Summary: Experiments on the DIII-D tokamak have pushed the operational limits of wide pedestal quiescent H-mode plasmas towards increased ITER relevance by demonstrating well-matched plasma shape and zero injected torque. Wide pedestal QH-modes, with enhanced edge transport generated by turbulence or a limit cycle oscillation, are seen as a promising regime for future power producing devices.
Article
Physics, Fluids & Plasmas
Ehab Hassan, D. R. Hatch, M. R. Halfmoon, M. Curie, M. T. Kotchenreuther, S. M. Mahajan, G. Merlo, R. J. Groebner, A. O. Nelson, A. Diallo
Summary: This study presents a simulation of microtearing mode (MTM) in the H-mode pedestal of an ELMy H-mode DIII-D discharge. The simulations show distinct frequency bands in the magnetic spectrogram, which correspond closely with the MTMs centered at the peak of the omega* profile. The study highlights the importance of global treatment for accurately reproducing the detailed band gaps of the low-n fluctuations.
Article
Physics, Fluids & Plasmas
Zeyu Li, Xi Chen, C. M. Muscatello, K. H. Burrell, Xueqiao Xu, Ben Zhu, Rongjie Hong, T. H. Osborne, B. A. Grierson, T. L. Rhodes, T. Y. Xia, G. R. McKee, Z. Yan, Guanying Yu
Summary: The QH mode discovered on DIII-D is a promising high confinement mode with characteristics like low rotation, high energy confinement, and edge localized mode-free operation. Simulations revealed two MHD-scale instabilities at the edge of the QH mode plasmas, offering insights into the pedestal stability and turbulence dynamics.
Article
Physics, Fluids & Plasmas
W. Guttenfelder, R. J. Groebner, J. M. Canik, B. A. Grierson, E. A. Belli, J. Candy
Summary: This paper presents linear and nonlinear gyrokinetic analyses in the pedestal region of two DIII-D ELMy H-mode discharges, showing the impact of divertor configurations on pedestal profiles. The study finds that electron temperature gradients are correlated with ETG instability thresholds, leading to significant contributions to electron heat fluxes.
Article
Physics, Fluids & Plasmas
K. Barada, T. L. Rhodes, S. R. Haskey, R. Groebner, A. Diallo, S. Banerjee, L. Zeng, Z. Yan, J. Chen, F. Laggner, G. Wang
Summary: New observations show that pedestal localized turbulence plays a significant role in ion and electron heat fluxes during ELMs, with density fluctuation at ITG and TEM scales being influenced by pedestal temperature gradients and E x B shear. These observations provide insight into improving pedestal predictive capabilities for future fusion devices.
Article
Physics, Fluids & Plasmas
K. Li, L. L. Lao, G. Q. Li, J. McClenaghan, X. Jian, T. Osborne, T. E. Evans, S. P. Smith, O. M. Meneghini, P. B. Snyder
Summary: Helium (He) plasmas are used to test systems and plasma diagnostics during the ITER non-nuclear phase, with good agreement found between pedestal width and height in recent experiments. The EPED/REPED pedestal model is applicable for predicting helium plasma pedestal structure and indicates similarities in pedestal height between helium and deuterium (D) plasmas, with helium having a slightly wider pedestal.
Article
Physics, Fluids & Plasmas
E. Lazzaro, F. Causa, G. Gervasini, F. Ghezzi, D. Borodin, I Borodkina, D. Douai, A. Huber, E. Pawelec, E. Solano, M. Sertoli, A. Widdowson
Summary: A modeling analysis is conducted to investigate the impact of W dust influx on the L-H-L mode transition in JET D and DT discharges. The study utilizes an upgraded version of the ballistic code DUSTTRACK and a new code PELLYTIX for dust ablation modeling. The results show that a reasonable amount of dust release does not have disastrous effects on high regime tokamak operation.
Article
Physics, Fluids & Plasmas
M. T. Curie, D. R. Hatch, M. Halfmoon, J. Chen, D. L. Brower, E. Hassan, M. Kotschenreuther, S. M. Mahajan, R. J. Groebner
Summary: In this study, the experimental data on electromagnetic fluctuations in DIII-D was compared with detailed gyrokinetic simulations using GENE. The unique capability of the Faraday-effect radial interferometer-polarimeter (RIP) diagnostic in measuring internal fluctuations of magnetic fields was utilized.
Article
Physics, Fluids & Plasmas
H. Q. Wang, R. Hong, X. Jian, T. L. Rhodes, H. Y. Guo, A. W. Leonard, X. Ma, J. G. Watkins, J. Ren, B. A. Grierson, M. W. Shafer, F. Scotti, T. H. Osborne, D. M. Thomas, Z. Yan
Summary: The integration of a high-performance core and a dissipative divertor, or "core-edge integration," is seen as a critical issue in designing future fusion reactors. This letter presents the first experimental evidence of electron turbulence at the DIII-D H-mode pedestal, which correlates with pedestal broadening and facilitates core-edge integration. The turbulence is enhanced by high η_e (η_e = L_n / L_T_e) due to a strong shift between density and temperature profiles associated with a closed divertor. This wide pedestal, coupled with a closed divertor, provides a solution to the core-edge integration issue in future fusion reactors.
Article
Physics, Fluids & Plasmas
J. Chen, X. Jian, D. L. Brower, S. R. Haskey, Z. Yan, R. Groebner, H. Q. Wang, T. L. Rhodes, F. Laggner, W. Ding, K. Barada, S. Banerjee
Summary: A new comprehensive set of evidence shows that Micro-Tearing Modes (MTMs) dominate electron heat transport in the pedestal of H-mode experiments in the DIII-D tokamak. By scanning pedestal collisionality, the experiment investigates the role of MTMs and observes broadband magnetic and density fluctuations that are consistent with MTMs. The results suggest that MTMs could regulate the pedestal electron heat transport.
Editorial Material
Multidisciplinary Sciences
Yasmin Andrew, Eun-jin Kim
Summary: The high confinement mode (H-mode) is the standard operating scenario for fusion in toroidal confinement devices. Access to and understanding of the H-mode have been actively researched in magnetically confined fusion programmes worldwide. Recent progress in experimental capabilities, theoretical development, and modelling have advanced the understanding of the intricate dynamics of the H-mode phase. The 'H-mode transition and pedestal studies' Special Issue provides a comprehensive overview of recent progress in H-mode research, including experimental studies, theoretical inquiry, and computational modelling.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Instruments & Instrumentation
M. R. Major, G. R. McKee, B. Geiger, D. J. Den Hartog, K. Jaehnig, C. Seyfert, D. R. Smith, S. D. Stewart, Z. Yan
Summary: The new high radial resolution 2D multichannel Charge eXchange Imaging (CXI) diagnostic at DIII-D will measure carbon density fluctuations and access higher k(r) instabilities predicted in the steep-gradient region of the H-mode pedestal.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Physics, Fluids & Plasmas
Santanu Banerjee, S. Mordijck, K. Barada, L. Zeng, R. Groebner, T. Osborne, T. L. Rhodes, P. B. Snyder, B. Grierson, A. Diallo
Summary: Observations in DIII-D show that transitioning heating from pure neutral beam injection to predominantly electron cyclotron heating results in a 40% decrease in ELM frequency, more regular ELM spacing, increased pedestal fluctuations in magnetics and density, and differences in the recovery of pedestal profiles. The increase in fluctuations in the ECH-dominated discharge is proposed to cause enhanced fluctuation-driven transport and slower pedestal recovery, ultimately leading to a reduction in ELM frequency.
Article
Physics, Fluids & Plasmas
M. R. Halfmoon, D. R. Hatch, M. T. Kotschenreuther, S. M. Mahajan, A. O. Nelson, E. Kolemen, M. Curie, A. Diallo, R. J. Groebner, E. Hassan, E. A. Belli, J. Candy
Summary: Gyrokinetic simulations were used to study pedestal fluctuations in DIII-D discharge 174082, revealing contributions from electron temperature gradient-driven transport and neoclassical transport to electron heat flux. The presence of microtearing modes and MHD modes were found to likely account for the remaining energy losses in the electron and ion channels, respectively. The analysis suggests that both MHD modes and microtearing modes are simultaneously active, with MHD modes primarily affecting particle transport.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
G. M. Staebler, R. J. Groebner
Article
Materials Science, Multidisciplinary
A. W. Leonard, J. D. Elder, J. M. Canik, R. J. Groebner, T. H. Osborne
JOURNAL OF NUCLEAR MATERIALS
(2013)
Article
Physics, Fluids & Plasmas
L. W. Owen, J. M. Canik, R. J. Groebner, J. D. Callen, X. Bonnin, T. H. Osborne
Article
Physics, Fluids & Plasmas
P. B. Snyder, R. J. Groebner, J. W. Hughes, T. H. Osborne, M. Beurskens, A. W. Leonard, H. R. Wilson, X. Q. Xu
Article
Physics, Fluids & Plasmas
S. P. Smith, J. D. Callen, R. J. Groebner, T. H. Osborne, A. W. Leonard, D. Eldon, B. D. Bray
Article
Physics, Fluids & Plasmas
R. J. Groebner, C. S. Chang, J. W. Hughes, R. Maingi, P. B. Snyder, X. Q. Xu, J. A. Boedo, D. P. Boyle, J. D. Callen, J. M. Canik, I. Cziegler, E. M. Davis, A. Diallo, P. H. Diamond, J. D. Elder, D. P. Eldon, D. R. Ernst, D. P. Fulton, M. Landreman, A. W. Leonard, J. D. Lore, T. H. Osborne, A. Y. Pankin, S. E. Parker, T. L. Rhodes, S. P. Smith, A. C. Sontag, W. M. Stacey, J. Walk, W. Wan, E. H. -J. Wang, J. G. Watkins, A. E. White, D. G. Whyte, Z. Yan, E. A. Belli, B. D. Bray, J. Candy, R. M. Churchill, T. M. Deterly, E. J. Doyle, M. E. Fenstermacher, N. M. Ferraro, A. E. Hubbard, I. Joseph, J. E. Kinsey, B. LaBombard, C. J. Lasnier, Z. Lin, B. L. Lipschultz, C. Liu, Y. Ma, G. R. McKee, D. M. Ponce, J. C. Rost, L. Schmitz, G. M. Staebler, L. E. Sugiyama, J. L. Terry, M. V. Umansky, R. E. Waltz, S. M. Wolfe, L. Zeng, S. J. Zweben
Article
Physics, Multidisciplinary
Weigang Wan, Scott E. Parker, Yang Chen, Zheng Yan, Richard J. Groebner, Philip B. Snyder
PHYSICAL REVIEW LETTERS
(2012)
Article
Physics, Fluids & Plasmas
W. M. Stacey, M-H. Sayer, J-P. Floyd, R. J. Groebner
PHYSICS OF PLASMAS
(2013)
Article
Physics, Fluids & Plasmas
Santanu Banerjee, S. Mordijck, K. Barada, L. Zeng, R. Groebner, T. Osborne, T. L. Rhodes, P. B. Snyder, B. Grierson, A. Diallo
Summary: Observations in DIII-D show that transitioning heating from pure neutral beam injection to predominantly electron cyclotron heating results in a 40% decrease in ELM frequency, more regular ELM spacing, increased pedestal fluctuations in magnetics and density, and differences in the recovery of pedestal profiles. The increase in fluctuations in the ECH-dominated discharge is proposed to cause enhanced fluctuation-driven transport and slower pedestal recovery, ultimately leading to a reduction in ELM frequency.
Article
Physics, Fluids & Plasmas
W. Guttenfelder, R. J. Groebner, J. M. Canik, B. A. Grierson, E. A. Belli, J. Candy
Summary: This paper presents linear and nonlinear gyrokinetic analyses in the pedestal region of two DIII-D ELMy H-mode discharges, showing the impact of divertor configurations on pedestal profiles. The study finds that electron temperature gradients are correlated with ETG instability thresholds, leading to significant contributions to electron heat fluxes.
Article
Physics, Fluids & Plasmas
M. T. Curie, J. L. Larakers, D. R. Hatch, A. O. Nelson, A. Diallo, E. Hassan, W. Guttenfelder, M. Halfmoon, M. Kotschenreuther, R. D. Hazeltine, S. M. Mahajan, R. J. Groebner, J. Chen, C. Perez von Thun, L. Frassinetti, S. Saarelma, C. Giroud, M. M. JET Contributors, M. M. Tennery
Summary: This article presents a global reduced model for slab-like microtearing modes (MTMs) in the H-mode pedestal, which reproduces distinctive features of experimentally observed magnetic fluctuations, such as chirping and discrete frequency bands at noncontiguous mode numbers. The key insight underlying this model is that MTM instability is enabled by the alignment of a rational surface with the peak in the profile of the diamagnetic frequency. A fast yet accurate reduced model for MTMs enables rapid interpretation of magnetic fluctuation data from a wide range of experimental conditions to help assess the role of MTM in the pedestal.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
M. R. Halfmoon, D. R. Hatch, M. T. Kotschenreuther, S. M. Mahajan, A. O. Nelson, E. Kolemen, M. Curie, A. Diallo, R. J. Groebner, E. Hassan, E. A. Belli, J. Candy
Summary: Gyrokinetic simulations were used to study pedestal fluctuations in DIII-D discharge 174082, revealing contributions from electron temperature gradient-driven transport and neoclassical transport to electron heat flux. The presence of microtearing modes and MHD modes were found to likely account for the remaining energy losses in the electron and ion channels, respectively. The analysis suggests that both MHD modes and microtearing modes are simultaneously active, with MHD modes primarily affecting particle transport.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Fluids & Plasmas
J. Chen, X. Jian, D. L. Brower, S. R. Haskey, Z. Yan, R. Groebner, H. Q. Wang, T. L. Rhodes, F. Laggner, W. Ding, K. Barada, S. Banerjee
Summary: A new comprehensive set of evidence shows that Micro-Tearing Modes (MTMs) dominate electron heat transport in the pedestal of H-mode experiments in the DIII-D tokamak. By scanning pedestal collisionality, the experiment investigates the role of MTMs and observes broadband magnetic and density fluctuations that are consistent with MTMs. The results suggest that MTMs could regulate the pedestal electron heat transport.
Article
Physics, Fluids & Plasmas
Weigang Wan, Yang Chen, Scott E. Parker, Richard J. Groebner
PHYSICS OF PLASMAS
(2015)
Article
Physics, Fluids & Plasmas
J. -P. Floyd, W. M. Stacey, R. J. Groebner, S. C. Mellard
PHYSICS OF PLASMAS
(2015)